The benefits of exercise in health promotion and disease prevention have been widely documented. However, determinants of exercise behavior among older Mexican-Americans (MA) remains an understudied area. The specific aim of the Determinants of Exercise in the Elderly Study (DEES) is to determine what factors influence exercise behavior among older Mexican-Americans (MA). We will recruit 250 MA elders and 250 non- Hispanic white (NHW) elders from their family physician's office, and conduct a comprehensive in-home evaluation designed to test a cohesive set of primary aims to enhance our understanding of how MA elders and NHW elders differ regarding: 1) exercise habits, energy expenditure and typical activities; 2) factors hypothesized to influence exercise behavior, such as: perceived self-efficacy toward exercise; perceived barriers to exercise; models of exercise behavior; friend and family (social) support for exercise; normative beliefs about exercise; and perceived falls efficacy or fear of falling, 3) the relative impact of major medical comorbidity and cognitive, physical, affective and social support status on exercise, and 4) the relationship between exercise and functional independence in activities of daily living. DEES will be the first comprehensive cross-sectional study to examine determinants of exercise behavior among MA elders. The ultimate goal of DEES is to devise a culturally-appropriate exercise intervention program for MA elders, in order to enhance their exercise activity and allow them to share fully in the benefits of exercise.